1. Field of the Invention
This invention relates to an image reading apparatus for use in a facsimile apparatus, a copying apparatus or the like.
2. Related Background Art
The construction of an image reading apparatus according to the prior art is schematically shown in FIG. 3 of the accompanying drawings. This image reading apparatus 100 is utilized to read the image information of an original in an apparatus such as a copying apparatus or a facsimile apparatus.
In FIG. 3, the reference numeral 101 designates a paper feeding roller for feeding an original, not shown, to a reading position P1, the reference numeral 102 denotes a paper feeding pinch roller, the reference numeral 103 designates a paper discharging roller for carrying out the read original, and the reference numeral 104 denotes a paper discharging pinch roller. The reference numeral 105 designates an upper original guide forming the upper portion of an original conveying route, the reference numeral 106 denotes a lower original guide forming the lower portion of the original conveying route, the reference numeral 107 designates a body frame, the reference numeral 108 denotes an original keeping plate for preventing the floating of the original at the reading position P1, the reference numeral 109 designates a mounting metal fitting for fixing an intimate contact type image sensor unit 110 which will be described later to the body frame 107, and the reference numeral 110 denotes an intimate contact type image sensor unit for reading the information of the original.
The intimate contact type image sensor unit 110 is comprised of a light source 110a for illuminating the read surface of the original, an optical sensor 110b for converting the image information of the original into an electrical signal, a SELFOC lens (trade mark: Nippon Plate Glass Co., Ltd.) 110c for imaging the image information of the original illuminated by the light source 110a on the optical sensor 110b, cover glass 110d for guiding the original near the reading position P1, a sensor chassis 110e for positioning and fixing the light source 110a, the optical sensor 110b and the SELFOC lens 110c, a guide Mylar 110f for eliminating the gap between the lower original guide 106 and the intimate contact type image sensor unit 110 and smoothly guiding the original from the lower original guide 106 to the reading position P1, and a sensor frame 110g for containing the cover glass 110d and the sensor chassis 110e therein.
However, in the above-described example of the prior art, the intimate contact type image sensor unit 110 is designed to be mounted on the body frame 107 by the mounting metal fitting 109, and this has led to the following problems.
The intimate contact type image sensor unit 110 is independent of the lower original guide 106 and therefore, when the mounting metal fitting is deformed with the lapse of time or the relative position of the lower original guide 106 and the body frame 107 is changed, the mounting position accuracy of the intimate contact type image sensor unit 110 goes wrong and it becomes impossible to effect good image reading.
Also, when the intimate contact type image sensor unit 110 is to be mounted on the body frame 107, the adjustment for putting out the reading position is necessary and the assembling property is low.
Further, the mounting metal fitting 109 itself for mounting the intimate contact type image sensor unit 110 on the body frame 107 and the guide Mylar 110f for preventing the original from colliding with the gap between the lower original guide 106 and the intimate contact type image sensor unit 110 are necessary, and necessarily the number of parts and the number of assembling steps become many and this causes an increase in cost.